Kamado type grills have been in use for many years. Kamado type grills have increased in popularity, particularly for those individuals that desire to slow cook or smoke foods using charcoal and the like as a fuel source.
Early examples of Kamado grills are shown and described in U.S. Pat. No. 3,276,440 and U.S. Design Pat. No. D201,416. FIGS. 1A, 1B and 2 of this patent show a representative prior art Kamado type grill and a related slow cooking accessory. In general, such grills include a ceramic body 1 and a ceramic lid 2 which may be attached to the body with a hinge. The body 1 typically includes a side intake or draft door 3 to permit the intake of combustion air and the lid 2 includes a top vent 4 which permits hot air to exit. In this manner, air goes into the side draft door 3, is heated by the coals and circulates to the top vent 4 for discharge.
The interior of typical Kamado grills includes a firebox 5, also typically made of ceramic. The firebox 5 supports a fuel grate 6 spaced a short distance from the bottom of the body 1 and upon which charcoal or other fuel is placed. The firebox 5 fixes the location of the fuel grate 6 within the grill. The firebox 5 in turn supports an annular fire ring 7 which in turn supports the cooking grid 8 upon which the food to be cooked is placed. The fire ring 7 functions as a spacer to raise the cooking grid 8 above the fuel grate 6. In this configuration, a grill of this type is most often used for standard grilling, i.e., direct heat under the cooking grid with no heat deflecting barrier between the fuel grate and cooking grid.
The above described Kamado type grills are also used, and in fact are popular for, indirect or convection slow cooking. When this mode of cooking is desired, Kamado type grills typically use a plate-shaped insert 9 with upstanding legs 10 that forms a heat barrier or deflector between the fuel grate 6 and cooking grid 8, as shown generally in FIG. 2. See also, U.S. Publication No. 2014/0224750. Typically, the deflector plate 9 is also made of ceramic. In general, the ceramic heat deflector 9 is placed on top of and is supported by the fire ring 7, with legs 10 as part of or associated with the deflector 9 in an upstanding position. The cooking grid 8 is then placed on the legs 10. In this manner, the heat from the coals is supposed to be deflected by the deflector plate 9 and rise around the exterior recessed edges of the deflector plate 9 to cook the food by convection. The ceramic components are thought to aid in the slow cooking and/or smoking process by retaining heat. In addition, the structure and material of the grill are thought to conserve fuel during the slow cooking process.
A commercially available Kamado type grill is known as the Big Green Egg® by The Big Green Egg, Inc. (biggreenegg.com). This device is similar to that described above in FIGS. 1A, 1B and 2, and is further shown and described in U.S. Pat. No. 7,644,711. That patent discusses the general configuration of the Big Green Egg, but is more specifically directed to a spark arrestor and airflow control located on the side of the grill body near the bottom (see also related design Pat. Nos. D615,814 and D615,807). The embodiment shown in the above referenced utility patent describes the direct cooking configuration. When indirect or slow cooking is desired, a ceramic deflector plate with upstanding legs is typically placed upon the fire ring with the legs pointed upward. The cooking grate is then placed on top of the legs. The deflector plate is used to facilitate indirect cooking by providing a heat deflecting barrier between the cooking grid and the fuel grate. The ceramic deflector plate, in conjunction with the ceramic body and domed lid, are intended to radiate heat while preventing flames and heat from cooking the food too quickly. It is also believed that less fuel is consumed.
Other similar Kamado type grills are also available, such as the Kamado Series by Vision Grills (see visiongrills.com). These grills are similar in structure and operation to the Big Green Egg and also use ceramic for the main structural components. These grills also have a firebox that supports the fuel grate at a fixed position near the bottom of the grill body and combustion air intake/draft doors on the bottom side of the grill body. The basic design, as well as a side intake and an ash catcher system, is shown and described in U.S. Publication No. 2011/0283990 A1. These grills also have an available ceramic deflector plate with upstanding legs that is placed and functions as discussed above. Kamado Joe, by Premier Specialty Brands, is another commercially available Kamado type grill, which is also similar in structure and function to the Big Green Egg (see kamadojoe.com). This device also has an available ceramic deflector plate with upstanding legs that may be used for indirect or convection slow cooking. Like the other devices discussed above, the Kamado Joe has a fuel grate which is supported in a fixed position near the bottom of the grill by a firebox. It also has a side air intake and ash drawer (see U.S. Pat. No. D683,177). As indicated, the lid and body of the foregoing Kamado type grills are constructed of ceramic. In addition, the available deflector plates for these grills are also typically made of ceramic.
Another commercially available, Kamado type grill, is known as the Broil King Keg by Onward Manufacturing Co., Ltd., which is generally shown and described in U.S. Publication No. 2009/0308373 A1. The major components and overall shape are largely similar to the ceramic Kamado type grills discussed above. For example, this grill has a draft door on the bottom side of the grill body and a fuel grate at a fixed position near the bottom of the grill body. However, unlike the above described ceramic grills, the body and lid of the Broil King Keg grill is constructed of doubled walled steel with a plenum formed between the inner and outer steel shells. Although the identified published patent application describes that the plenum may be filled with air, in the preferred embodiment, as well as the commercial embodiment, the plenum between the double walls is filled with an insulating material, such as fiberglass. In addition, a deflector plate is available for the slow cooking mode, which is positioned between the fuel grate and cooking grid. The available deflector plate is described as preferably constructed from a solid piece of cast iron.
The commercially available Kamado type grills all suffer from several drawbacks. For example, the grills made from ceramic are exceedingly heavy and fragile. They are also expensive to ship and manufacture. In addition, ceramic does not release heat as well as other materials which impedes proper heating, convection and air flow and increases fuel consumption. Even the insulation filled, non-ceramic grill discussed above is heavy and cumbersome. And, the insulation is prone to becoming damp, which increases the weight and diminishes the insulating ability of the insulation.
In addition, all of the foregoing grills have fuel grates at a fixed position near the bottom of the grill. While such a position may be suitable for slow cooking by keeping the heat source further from the cooking surface, when these grills are used for direct cooking, the heat source is undesirably far from the cooking grid. This lack of flexibility requires the use of additional fuel, poor heating and can lead to uneven cooking.
Like the single position fuel grate, the side drafts or air intakes found on the known commercially available Kamado type grills are also a disadvantage in certain grilling situations. For example, the bottom side vent location may be suitable (but not ideal) for slow or convection cooking. However, even with slow cooking, the side draft provides uneven air flow and creates unbalanced combustion, which begins behind the side draft door. This inhibits proper combustion and reduces convection. And, when used for direct cooking, the side drafts do not permit the fuel to get as hot as may be desirable. Thus, temperature is often difficult to control and heat dispersion suffers.
It has also been determined that the ceramic and cast iron deflector plates used with the Kamado type grills often result in overcooking the food. This is because they are placed too close to the cooking grid and do not permit adequate air flow for convection or slow cooking. In addition, the materials used for the deflector plates, such as ceramic and cast iron, can overheat and become a cooking surface. This makes them too hot for desirable slow cooking. Moreover, known deflector plates can also make it difficult to add fuel, particularly when used for slow cooking or smoking, since cooking often takes place over many hours.
Because of the configuration of the fixed cooking grate, side draft air intake and the location and type of deflector plates used, the available Kamado type grills have less than optimal air flow and unbalanced combustion. As a result, more fuel is used, temperature control is difficult and cooking quality suffers. Moreover, the top vents of typical grills do not permit a high degree of adjustability. The present inventions overcome the above and other stated and inherent disadvantages.
Of course, standard charcoal grills are also well known and popular. Many of them are particularly useful for direct cooking. However, indirect cooking on many standard grills is otters more difficult, especially for the novice user. As discussed below, others have tried to provide standard grills that efficiently slow cook, but the results have not been successful.
For example, there are charcoal grills available that use a double lined grill body (but a single layer lid) to purportedly improve air flow and more evenly cook food indirectly. Various examples of such grills are shown and described in U.S. Publication No. 2014/016593 A1. In the embodiments discussed in this published application (e.g., FIGS. 5A and 5B), the draft or intake for the introduction of combustion air is a series of holes located on the upper side of the grill body. The body of such grills further includes an interior wall that is designed to purportedly direct the combustion air around the sides of the grill and to exit into the grill at various positions in relation to the fuel grate. Such grills are supposed to be advantageous for, among other things, use of the grill in windy conditions. However, the air flow is not ideal and the introduction of combustion air insufficient for properly heating the fuel. In addition, the fuel grate in such grills is in a fixed position that is not ideal for both direct and indirect cooking.
Finally, Danish Patent No. DK 176696 B1 (see also related published Application No. DK 200101276A) shows an insert for a grill. This insert is shaped like a bowl, having an enclosed bottom and upstanding sides (see also FIG. 3 of U.S. Publication No. 2014/0165993 A1). This technology is believed to be incorporated into a grill liner sold under the Dancook name by Saber Grills, LLC (see e.g., dancookusa.com/main/patentedtechnology.aspx). In this device, the fuel grate is supported by the liner near the bottom of the liner, which is designed to heat the air in the grill and to catch grease and ash. Combustion air is introduced through draft holes on the bottom of the grill body. However, the combustion air is then directed up from the draft holes between the insert and the grill body. Combustion air is ultimately introduced at a position above the fuel grate. This device also has a fixed position fuel grate and a single layer lid, although some standard gas grills are believed to incorporate a double layer lid. Among other things, the device leads to poor air flow and heat dispersion. In addition, the liner must be removed to clean out the ash. The present inventions overcome these and other disadvantages as well.
Thus, there is a need for a fuel efficient grill that is capable of effective direct and indirect cooking that overcomes the stated and unstated shortcomings of known grills. In addition, there is a need for improved air flow and air flow control, as well as the need for ease in the addition of fuel.